Phase Transformation and Its Effect on Mechanical Characteristics in Warm-Deformed Ti-29Nb-13Ta-4.6Zr Alloy

Abstract

Ti-29Nb-13Ta-4.6Zr (TNTZ) alloy has been extensively studied as it is promising for use in biomedical applications. Despite its potential, the effects of warm plastic deformation on the alloy have not yet been revealed. This study investigated the differences in phase constitution of two warm-deformed TNTZ alloys and revealed relevant mechanisms with particular attention to martensitic transformation. The influence of phase constituents on mechanical characteristics was discussed as well. The TNTZ alloy deformed at 823 K possessed alpha, beta, and omega phases as well as alpha '' martensite, and demonstrated a low Young's modulus and double-yielding phenomenon. In contrast, the alloy deformed at 723 K had no martensite but more omega phase, leading to increased strength, hardness, and Young's modulus. The absence of alpha '' martensite in the alloy deformed at 723 K was interpreted in light of beta-stability of the parent phase and reduced M-s temperature.